Abstract:

β-N-acetyl-D-glucosaminidase (EC3.2.1.52) was purified from the pupae of Helicoverpa armigera by ammonium sulfate fractionation and chromatography on Sephadex G-200 and DEAE cellulose. The purified enzyme preparation was homogeneous as judged by polyacrylamide gel electrophoresis. It was found that the specific activity of the enzyme was 2 678.79 U/mg. The optimal pH value was 5.63 and the optimal temperature 55℃. The enzyme was stable in the pH ranges of 4 to 8 under 37℃. The enzyme follows typical Michaelis Menten kinetics for the hydrolysis of pNP-β-D-GlcNAc and the K_m and V_m values were 0.16 mmol/L and 10.73 μmol·L^-1·min^-1, respectively. The activation energy of the enzyme for the hydrolysis of pNP-β-D-GlcNAc was 66.24 kJ/mol.

Key words: Helicoverpa armigera, β-N-acetyl-D-glucosaminidase, isolation and purification, kinetics, stability